1. Field of the Invention
This invention relates to a disc recording and/or reproducing apparatus employed for an optical recording medium adapted for recording and/or reproducing information signals by a light beam, such as an optical disc or a magneto-optical disc. More particularly, it relates to such apparatus provided with a mistaken insertion inhibiting mechanism for permitting loading of only a disc cartridge housing such optical disc or magneto-optical disc and inhibiting loading of a disc cartridge housing other types of discs.
2. Description of Related Art
Among optical discs employing a light beam for recording and/or reproducing information signals, there are an optical disc used for only reproduction of information signals, and a magneto-optical disc adapted for erasing recorded signals for re-recording other information signals.
The optical disc is provided with a reflection layer formed of a metal thin film, such as aluminum, which reflection layer is applied as a thin film on a disc substrate having a pattern of recesses and lands formed after information signals by e.g. injection molding. Information signals recorded on the optical disc as a pattern of pits and grooves on the optical disc are read from the disc by radiating a beam of coherent light, such as a laser beam, and detecting changes in intensity of the reflected light beam due to interference produced when the light beam is reflected by the reflection layer for discriminating the pattern of the pits and grooves.
The magneto-optical disc has a signal recording layer formed by a perpendicular recording thin magnetic film formed on a light-transmitting disc substrate. This signal recording layer is heated to a temperature higher than the Curie temperature by radiation of a laser beam, while having its direction of magnetization inverted by the application of an external magnetic field to effect writing of information signals. The information signals written on the signal recording layer are read by radiating a plane polarized light flux, such as a laser beam, on the signal recording layer and by detecting changes in the direction of light polarization due to the Kerr effect on reflection of the light flux by the signal recording layer for discerning the changes in the direction of magnetization.
For writing and/or reading information signals on or from the optical disc, a disc recording and/or reproducing apparatus, constituted by an optical pickup device adapted for radiating the light beam to the disc and a magnetic head device for applying the external magnetic field. The optical pickup device is arranged for facing a major surface of the optical disc, that is a disc substrate, and adapted for radiating the converged light to the disc and detecting the laser light reflected from the disc. On the other hand, the magnetic head device is arranged on the opposite side of the optical pickup device, with the disc in-between, for facing the signal recording layer of the optical disc, and is adapted for applying the magnetic field to the signal recording layer of the optical disc.
With the present disc recording and/or reproducing apparatus, the optical disc is held and rotated by a rotational driving device for the optical disc, while the optical pickup device and the magnetic head device are moved radially of the disc for writing and/or reading the information signals on or from the recording region of the optical disc.
As an optical disc and a magneto-optical disc, employed as a recording medium for this type of the disc recording and/or reproducing apparatus, a disc having a diameter of approximately 3.5 inches is proposed. These discs, that is the optical disc and the magneto-optical disc, are constituted as a disc cartridge by being housed in a cartridge main body for preventing pollution due to deposition of dust and dirt and contact of hand or finger while the disc is not in use. A disc cartridge 201, such as shown in FIG. 1, is proposed as a disc cartridge housing a disc 202, such as the optical disc or the magneto-optical disc.
The optical disc cartridge 201, shown in FIG. 1, is constituted by a cartridge main body 203, and a shutter member 211 movably mounted on the cartridge main body 203.
Meanwhile, a chucking hub 202a is mounted at a mid part of one of the major surfaces of the disc 202 housed within the disc cartridge 201 for chucking the disc with respect to the disc rotating driving unit provided within the disc recording and/or reproducing apparatus in which the optical disc cartridge 201 is loaded.
The cartridge main body 203 housing the optical disc 202 is formed as a rectangle of a size large enough to accommodate the disc 202 which is 3.5 inches in diameter. The side of the major surface of the rectangle mounting the shutter member 211 is 90 mm long, with the other side of the major surface of the rectangle normal thereto being 94 mm. The cartridge main body 203 has a thickness of 6 mm. The cartridge main body 203 is made up of an upper cartridge half 205 and a lower cartridge half 204 which are abutted and secured to each other by set screws, ultrasonic welding or with the aid of an adhesive.
The lower half 204 of the cartridge main body 203 has a first aperture 206 for laying a chucking hub 202a of the optical disc 202 and a part of the signal recording region of the disc 202 to outside across the inner and outer peripheries of the disc. The first aperture 206 is formed as an elongated opening extending from a front side 209 toward the center of the cartridge main body 203.
When the optical disc cartridge 201 is loaded in the disc recording and/or reproducing apparatus, the first aperture 206 causes the chucking hub 202a to face a disk table of the disc rotating driving unit adapted for rotating the optical disc 202, while causing the signal recording section of the optical disc 202 to face the optical pickup device radiating an optical beam to the signal recording section.
The upper half 205 is provided with a second aperture, not shown, at a position in register with the first aperture 206 of the lower half 204. This second aperture, provided in proximity to the front side 209 of the cartridge main body 203, is a rectangular opening having a size to lay a part of the other major surface of the optical disc 202 to outside across the inner and outer peripheries of the disc. When the disc cartridge 201 is loaded in position in the disc recording and/or reproducing apparatus, the second aperture causes the other major surface of the optical disc 202 to face the magnetic head apparatus.
Meanwhile, at opening ends of the first aperture 206 and the second aperture on the front side 209 of the cartridge main body 203, the part of the cartridge main body directed towards the front side 209 is recessed at 206a, 210a to permit facilitated entrance of the magnetic head device and the optical pickup device in close facing relation with respect to the major surfaces of the optical disc 202. That is, the mid part of the cartridge main body 203 in proximity to the front side 209 is reduced in thickness in an area thereof in register with the first aperture 206 and the second aperture.
The shutter member 211 for opening or closing the first, aperture 206 and the second aperture is movably mounted on the cartridge main body 203. The shutter member 211 has a substantially U-shaped cross-section and is made up of a first plate section 212 adapted for closing the first, aperture 206 of the lower half 204, a second plate section 213 extending parallel to the first, section 212 and adapted for closing the second aperture, and a connecting web 214 interconnecting the proximal sides of the plate sections 212, 213.
The first plate section 212 is in the form of an elongated rectangle of a narrow width and of a size large enough to close the first aperture 206 of the lower half 204. The distal side of the first plate section 212 is pressed by a shutter pressor plate 215 mounted on the outer lateral side of the lower half 204 to prevent the first plate section 212 from being floated from the cartridge main body 203. On the proximal side of the first plate section 212, connected to the web 214, a first engaging pawl 217 adapted for being engaged with a first slide guide groove 216 provided on the outer lateral side of the lower half 204 is bent towards the second plate section 213. The second plate section 213 is in the form of a rectangle which is of a size large enough to close the second aperture provided in the upper half 203.
A shutter member guide arm section 218 is provided by extending the first and second plate sections 212, 213 from a lateral side of the web 214 in the direction of movement of the shutter member 211. This shutter member guide arm section 218 is provided between the recesses 206a, 210a formed on the front side 209 of the cartridge main body 203 and is of a width equal to that of the recesses 206a or 210a. When the shutter member 211 is moved to a position of opening the first aperture 206 and the second aperture, the guide arm section is located in register with the recesses 206a, 210a for exposing these recesses.
A U-shaped fitting clamping section 219 is provided at an end of the guide arm section 218 for clamping and fitting the front side 209 of the cartridge main body 203. The distal end of a tongue of the fitting holding section 219 extended over the lower half 205 is formed with a bent engaging pawl 221 adapted for being engaged with a second guide groove 220 formed on the outer lateral side of the lower half 204 for extending parallel to the first guide groove 216.
The shutter member 211 is fitted to the cartridge main body 203, with the fitting holding section 219 clamping the front side 209 of the cartridge main body 203 and with the first and second engaging pawls being engaged in the first and second guide grooves 216, 220, so that the shutter member may be moved in stability in a manner free from the risk of accidental extrication from the cartridge main body 203.
A spring retainer 222, adapted for retaining an end of a torsion coil spring, not shown, provided in the cartridge main body 203, is provided in a part of the connecting web 214. This torsion coil spring is adapted for perpetually biasing the shutter member 211 in a direction of closing the first aperture 206 and the second aperture of the lower half 205. The spring retainer 222 is bent substantially parallel to the first and second plate sections 212, 213 towards the inner side of the cartridge main body 203 so that the one end of the torsion coil spring is retained by the distal end of the spring retainer 222. Meanwhile, the other end of the torsion coil spring is retained by the forward corner of the cartridge main body 203.
The above described shutter member 211 may be moved between the position of closing the first aperture 206 and the second aperture and a position of opening these apertures, as indicated by an arrow C in FIG. 1.
The front side 209 of the cartridge main body 203 is formed with a notch 224 adapted for being engaged by shutter opening means, such as a shutter opening pin, of the disc recording and/or reproducing apparatus, for maintaining the first and second apertures in the opened state when the shutter member 211 is moved by the Shutter opening means. The notch 224 is formed as a groove at a position faced by the lateral side of the fitting holding section 219 of the Shutter member 211 when the first and the second apertures have been opened.
On lateral sides 207, 208 of the cartridge main body 203, guide flanges 201c, 201d, 201e and 201f are provided for extending from the front side 209 towards the rear side of the cartridge main body 203 in a direct, ion parallel to the inserting direction of the optical disc cartridge 201 into the disc recording and/or reproducing apparatus. These guide flanges 201c to 201f are flush with the upper and lower major surfaces of the cartridge main body 203. That is, these guide flanges are approximately 94 mm long and 1 mm in width, as indicated by arrows t1 and t3, and are projected from the cartridge main body 203 by a distance of 0.5 mm. Guide grooves 201a, 201b are defined by the guide flanges 201c, 201d and by guide flanges 201e, 201f, respectively. The distance between the guide flanges 201c, 201d and that between the guide flanges 201e, 201f, that is the width t2 of each of the guide grooves 201a, 201b is 4 mm. Meanwhile, the cartridge main body 203 has a width along the direction of movement of the shutter member 211, inclusive of the guide flanges, is 90 mm.
The lower half 204 is provided with a pair of engaging holes 225, 226 engaged by positioning pins, not shown, adapted for setting the horizontal loading position of the disc cartridge 201 when the disc cartridge is loaded in position in the disc recording and/or reproducing apparatus. A mistaken recording inhibiting member 227, adapted for indicating if information signals may be written on the optical disc 202, is provided on the lower half 204 in proximity to the engaging hole 226. An engaging notch 228, adapted for being engaged by an entraining pin provided in a loading mechanism of the disc recording and/or reproducing apparatus, is provided towards the front of the lateral side 207 of the cartridge main body 203.
Meanwhile, a magnetic disc is used widely as a recording medium for information signals. This magnetic disc is made up of a film-shaped base member coated with a magnetic medium. Since the magnetic disc is extremely fragile, it is constituted as a magnetic disc cartridge by being housed in a tough cartridge main body to assure protection and handling ease. A typical magnetic disc cartridge is disclosed in U.S. Pat. No. 4,918,559.
Similarly to the above described optical disc cartridge, the magnetic disc cartridge houses a magnetic disc which is 3.5 inches in diameter.
The magnetic disc cartridge 301 is hereinafter explained by referring to FIG. 2.
Similarly to the optical disc 202, accommodated in the optical disc cartridge 201, the magnetic disc cartridge 301 is provided with a cartridge main body 303 of a size large enough to accommodate a magnetic disc 302 having a diameter of 3.5 inches. Since the cartridge main body 303 is of the size large enough to accommodate the magnetic disc 302 which, similarly to the optical disc 202, is 3.5 inches in diameter, the cartridge main body 303 is similar in plan shape and size to the cartridge main body 203 constituting the optical disc cartridge 201. However, since the magnetic disc 302 is thinner than the optical disc 202, the cartridge main body 303 housing the magnetic disc 303 is thinner in thickness than the cartridge main body housing the optical disc 202. The cartridge main body 303 has a thickness T equal to 3 mm.
Meanwhile, the cartridge main body 303 is similarly provided with a recording/reproduction aperture 310 for laying the signal recording surface of the magnetic disc 302 to outside across the inner and outer peripheries of the disc and a shutter member 311 is movably mounted for opening or closing the aperture 310. This shutter member 311 is provided with a plate section 313 formed with an aperture 318 for laying the recording/playback aperture 310 to outside. This shutter member 311 is moved relative to the cartridge main body 303 so that, when the aperture 318 formed in the plate section 313 is moved as far as a position of facing the recording/playback aperture 310, the aperture 310 is opened and when the aperture 318 is moved as afar as a position of not facing the recording/playback aperture 310, the aperture 310 is closed.
Thus the optical disc cartridge 201, housing the optical disc 202 3.5 inches in diameter, and the magnetic disc cartridge 301, housing the magnetic disc 302, similarly 3.5 inches in diameter, are similar as far as the plan shape and the plan size, except the thickness, of the cartridge main body 203 and the cartridge main body 303, are concerned.
Meanwhile, such a disc recording and/or reproducing apparatus is proposed, in which a cartridge load/unload opening is provided in the main body of the apparatus, and the optical disc cartridge 201 is adapted to be introduced into and detached from the main body of the apparatus by means of the load/unload opening. The optical disc cartridge 201, inserted into and removed out of the apparatus via this load/unload opening, is loaded onto and unloaded from a cartridge loading section within the main body of the apparatus by means of a loading unit provided in the main body of the apparatus.
The cartridge load/unload opening is of a size large enough to introduce the optical disc cartridge 201 therethrough, that is, of a width approximately equal to the width of the side of the disc cartridge 201 provided with the shutter member 201, and a height approximately equal to the thickness of the optical disc cartridge 201. Consequently, not only the optical disc cartridge 201, but also the magnetic disc cartridge 301, which is of the same plan size as that of the disc cartridge 201 except the thickness, may be introduced via this cartridge load/unload opening.
With the above described disc recording and/or reproducing apparatus, employing the disc cartridge 201, the loading unit is activated even when the magnetic disc cartridge 301 is introduced. Since the loading unit is designed for loading the optical disc cartridge 201 thicker than the magnetic disc cartridge 301, if the magnetic disc cartridge 301 is introduced through error, it is caught by loading unit components or components of the guide unit, so that the magnetic disc cartridge can not be taken out of the disc recording and/or reproducing apparatus, or both the loading unit and the magnetic disc cartridge may be damaged. Besides, there is a risk that the magnetic disc 302 within the magnetic disc cartridge 301 or recording and/or reproducing means for information signals, such as magnetic head device or the optical pickup device provided in the main body of the apparatus, may also be damaged.